Interactive Water and Nitrogen Effects on Senescence of Maize. I. Leaf Area Duration, Nitrogen Distribution, and Yield

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Abstract
Stress effects on leaf senescence are important for maize (Zea mays L.), since production of new photosynthetic area is genetically pre‐determined. Interactive effects of water and N deficits on water potential components, green leaf area (GLA) duration, and N and biomass allocation during grain filling were evaluated in a 2‐yr field study conducted on Yolo loam (fine‐silty, mixed, nonacid, thermic Typic Xerorthents) under four treatments: 180 kg N/ha applied at planting, with (NI) and without (ND) irrigation; and no N fertilizer, with (OI) and without (OD) irrigation. Leaves of low N plants had reduced capacity for solute accumulation, and both water and N deficits caused 0.1‐ to 0.5‐MPa reductions in midday leaf turgor. Total GLA was smallest in the OD treatment, but senescence during grain filling was greatest in the ND treatment because of a high transpiration demand and a high reproductive sink demand for N. Ear removal reduced the rate of post‐anthesis leaf N decline of all treatments, and plants in the ND treatment showed a significant reduction in leaf senescence rate when ears were prevented. Grain yield of the OD treatment was 2 = 0.92) to final grain dry weight.
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